Does the Suhr RL have a Line Out Level control for the Line Out? If not, you are sort of at the mercy of how much power the tube amp is delivering for the level of your Line Out signal. My reactive load is a Rivera and it doesn’t have a Line Out Level control. So my cranked Super Lead yielded a really hot Line Out level. My solution was to use a second speaker cable to a Suhr ISO Line Out box. That has a Level control as well as phase flip switch. That is my line level into the rack.
And also, Line Levels are not all created equal it would appear. Look for
@psychodave thread about an old line out box Suhr custom built for him before they even made the production Line Out box. I know my rig sounded better when I switched to using just the production Suhr ISO box for the line level signal.